Various Features Influencing Convection Initiation on

12 June 2002 during IHOP_2002*

Tammy M. WeckwerthTammy M. Weckwerth (NCAR)

WWRP Symposium on Nowcasting and Very Short Range Forecasting, Toulouse, France, 5-9 September 2005

*Work in Progress

Hanne V. MurpheyHanne V. Murphey (UCLA)Cyrille FlamantCyrille Flamant (CNRS)

Crystalyne R. PettetCrystalyne R. Pettet (US NWS) Roger M. WakimotoRoger M. Wakimoto (NCAR)

Sophie BastinSophie Bastin (NCAR)

GOES 11

Composite Radar

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12 June 2002

Are the intersections between the waves and outflow preferred regions for CI?

Why did CI occur here?

Are the rolls a factor in CI?

Does the mesolow play a role in CI?

2050 UTC

CI 19 km from drop line

• Incomplete soundings – only up to 6 km AGL (445 mb)• No drops in CI air mass

NE SW

Outflow boundary

Dropsonde Leg 2 – CAPE & CIN

ELDORA Observations of Waves

• ELDORA fields @ 900 m AGL

• Gravity waves in all fields: λ = 6-8 km• Consistent with P-3, MIPS, GOES-11 and radar

dBZe vr

div vort

ELDORA and Leandre II Wave Impacts

• ELDORA and Leandre II fields @ 400 m AGL• Periodic signature in q, div and vort: λ=6-8 km

km

OK Mesonet – 18 UTC – Mesolow Impact

• LLJ feeding region of interest• Dewpoints in the high 60s and low 70s

Freedom

Wind Direction

Wind Speed Mixing Ratio

Moisture Convergence

Freedom, OK MesonetMesolow Impact

• Local increase in southerly flow, perhaps due to mesolow – not observed further south

• Increase in moisture convergence

Roll Observations

• ELDORA reflectivity and winds @ 400 m AGL• 1.1 km in situ fields show rolls (λ~3.6 km) SE of TP

qθ

w

10 km

Preliminary results

• Mesolow may have aided in enhancing moisture convergence in CI region.

• Waves sampled by ground-based radar, satellite, in situ P-3, low-level MIPS w, ELDORA. Suggestion of Leandre II mixing ratio modulation caused by waves – may be important for CI.

• Rolls observed near CI location with radar and in-situ P-3 – may be important for CI.*

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GOES-11 Cloud Tracking

• 1st clouds formed along rolls

• Northern cloud formed near wave/outflow intersection

Ongoing work

• Closely examine ELDORA and Leandre II measurements near CI location

• Modeling study by Sophie Bastin (presented next)

Thank you.